Potatoes au Gratin - Dauphinoise Potatoes

Preparing the Cream Mixture

1. In a saucepan, combine the double cream, milk, chopped garlic and thyme, bay leaf, nutmeg along with the half of the salt, and black pepper.
2. Place the saucepan over medium heat and bring the mixture to a gentle simmer.
3. Let it simmer for about 5 minutes to infuse the flavors. Then, remove from heat and let it cool slightly while preparing the potatoes.

Preparing the Potatoes

1. Peel the potatoes and wash them thoroughly. Pat them dry with a kitchen towel.
2. Use a mandolin or the slicer attachment on your food processor to slice the potatoes. You can carefully slice the potatoes by hand using a sharp knife if you have enough time and patience. The slices should be approximately 3mm (⅛ inch).
3. Place the sliced potatoes in a large bowl and pour the cream mixture over them.
4. Give them a good stir, ensuring that all the potatoes are thoroughly coated with the creamy sauce.

Assembling the Layers

1. Preheat the oven to 180° C - 360° F (fan oven).
2. Remove the bay leaf from the cream mixture and discard it.
3. Grease a baking dish with the softened butter.
4. Arrange a layer of sliced potatoes at the bottom of the dish, slightly overlapping. The layers don’t have to be perfect.
5. Sprinkle a pinch of salt, and a dash of black pepper.
6. Pour a small amount of the cream mixture over the potatoes, just enough to cover them.
7. Continue layering with potatoes, seasoning, and sauce until you've used all your potato slices.
8. Ensure that each layer is mostly flat and that the potatoes are not overlapping excessively. Usually, you'll have around 2 to 3 layers, depending on the size of your dish.
9. Pour over the remaining sauce, and cover the baking dish with aluminum foil.

Baking the Dauphinoise

1. Place the dish in the preheated oven.
2. Bake for about 30 minutes, remove the foil and continue baking for another 20 minutes, or until the potatoes are tender when pierced with a knife.
3. Remove the dish from the oven, scatter the grated Gruyère or cheddar cheese over the potatoes, and bake for an additional 15 minutes until the top layer turns golden brown and the cheese is melted and bubbly.
4. Once baked, remove the dish from the oven and let it cool slightly before serving. This allows the layers to set.